'They were only interested in naval matters,' he said with an attempt at dignity, 'affecting the security of their own coastline.'

'And how precisely did the sinking of the SSN Cetacea affect the Chinese coastline?'

He didn't answer, and I realized he didn't even need to. Of course it was nothing to do with the Chinese coastline: it was to do with the summit conference in Vienna.

'Keep aver this side? someone was yelling, and I wound the window down for a better view and slowed the truck. Two men with shovels were out there levering a rusty Volkswagen clear of the ruts. I turned my front wheels and got the rear chains working at the surface and nudged the VW onto the cleared surface with its tyres slewing across the sand. It pulled his offside wing off but he was out of trouble now. One of the road gang picked up the wing and threw it across the snow.

'Keep going! Keep your wheels moving!'

The VW sent a cloud of exhaust gas into the air and I shut the window. 'Karasov,' I said, 'have you got a gun on you?'

He looked at me sulkily. 'No.'

He could be lying: his eyes hadn't given anything away. It occurred to me that he might have brought a gun along to use on someone or on himself.

'Are you taking me into a trap?

Because anything was possible now. A few minutes ago he'd been a blown sleeper dependent on me to get him across but now he could be anything, any kind of Judas working for London, Moscow and Peking, raking in pounds sterling, rubles and yen while he kept the product coming and reported to the KGB through a backstairs courier. Maybe all that frightened him was the idea of sitting next to someone who was going to see the bits of glass coming at him first and then the flat-nosed slug as it moved into the target just above the eyes.

'A trap?' He shook his head. 'Listen, I'm not as bad as that.' And suddenly he was crying, and I shut up for a while and let him get it done with. It was the strain, I suppose, and the feeling that he was letting everyone down — because they're like that, some of them, the mercenaries, the people who'll work for anyone who'll pay them, two at a time, three at a time, paying off the mortgage on their little place in Hampstead and looking for a bigger one, bribing the black market commissar in the back streets of Leningrad to put him higher on the list for a nice little Moscwicz, shifting a bank account from Paris to Cannes and commuting by Caravelle from wife to mistress and back, compared with which my good friend Karasov was doing rather less well for himself, stuck in a truck in the Arctic Circle in winter time and snuffling over his sins into a filthy handkerchief.

Snow exploded against the windscreen and Karasov shouted something as his head rocked back against the seat squab. Fright, that was all. The big scoop out there had swung across the line of traffic and lost half a ton of snow in the process. I stopped the truck and got out and stood on the running board and kicked the snow off the bonnet and if they'd wanted to squeeze the hairspring at this precise moment they could have blown my head off. The other drivers were rechristening the man in the scoop, clumsy prick, whoreson, pox-ridden idiot, so forth, not at all popular.

''Get moving! Come on, get moving?

I botched the gears in through their worn shafts and we went forward again, shunting into the truck ahead and sliding into the clearway and getting some speed up. No trap, then, according to Karasov's behaviour: I'd been overestimating things — whatever he'd been doing and whoever he'd been busy working for he was still a burnt-out case.

'If you've got a gun on you, Karasov, I don't want you to use it. Do you understand?' He didn't answer. 'We may run into a road check between here and the coast and I don't want you to pull a gun on anyone. Do you understand?

He flinched again and a hand disappeared and he brought out a Soviet military JK-3. I took it from him and checked the safety-catch and shoved the thing under the seat.

'Who are they using? Who are the Chinese using?'

'They're being serviced through Zurich.'

The Rinker cell. Rinker had been a Swiss. But they'd used local agents: the two men on the train, one of them a Latvian. I didn't know about the third man, the other man: he'd looked European.

So Peking was worried about Washington and Moscow getting round a table in Vienna next month and they'd seized a chance in a lifetime: if they could get hold of a tape or Karasov himself and hit the American news media with the message that the Soviets had indeed sunk the Cetacea with a hundred and five lives on board they could scuttle the summit conference and leave that on the bottom too.

'So why didn't you sell them the tape?' He didn't answer. 'Wasn't the money good enough?'

The truck ahead of us was putting on more speed and I took up the slack; we were making nearly forty kph over sanded ruts. There was a lot of honking behind us in the distance; I supposed the fanner's vehicle was blocking the road because he still couldn't find any petrol.

'They wanted me to go in front of journalists, in Moscow.'

'Didn't they know you'd done a tape for them?'

'Yes. They knew.'

'Then why — come on Karasov I want some fucking information.'

'They knew I had a tape but they said they wanted me to be there too at the broadcast.'

'What was their price?'

'A million US dollars.' I looked at him. 'So why didn't you take it?'

'I knew then how serious things were. There was some talk at the naval base about the summit conference having gone down with the submarine, that kind of thing. So I told my contact the tape had-'

'Your contact for Peking?'

'Yes. I told him the tape had been accidentally wiped out when I'd passed through one of the power-station rooms. They said they still wanted me to make a broadcast, and for the same money. They also said that if I wouldn't do it, they'd blow me to the KGB.'

'That was when you got out?'

'Yes.'

'I still don't understand why you turned them down.' He leaned towards me and a light came into his wet brown eyes. 'I was making a little on the side, don't you see, I was selling a few things to the Chinese from time to time because it wasn't doing London any harm, it wasn't anything I was keeping back from your people, it was simply a matter of duplication, don't you understand, I wasn't doubling, I was only augmenting my income. London came first with me. I'm not a man completely without loyalty, I didn't do anything that isn't done among — among-' he waved a gloved hand — 'among business people all over the world, but when I saw how serious things were, with the summit in jeopardy and the headlines talking about it every day, I backed out of my commitment with the Chinese and went to ground.'

'You turned down a million American dollars?'

'Yes. Do you think money is everything? Do you-'

'You got frightened, that was all, it got too big for you?' He gave a kind of sob and I kicked the throttle and started a slide and smashed the sidelight off an abandoned trailer with the rear of the truck and got control again, slowed again, it wasn't for me to judge the poor bastard, what the hell did I know about the things I'd do if the pressure got too much or a deal got too hot to handle, I wasn't this man and I hadn't faced what he had faced, I wasn't my brother's keeper, nor his judge.

'I would've done the same, Karasov. I would've got frightened.'

I don't think he heard me. He was a man of conscience, I suppose, and what he was trying desperately to rescue from the ashes was some kind of pride.

'Slow down! There's a detour! Slow dorm!'

More men waving, and a truck overturned and half-smothered under a snow drift, someone sitting by a fire he'd made from some oily rag, warming his hands while the black smoke rose like a dead vine from the ground to the winter sky.